Incidence and predictors of non-fatal drug overdose after release from prison among people who inject drugs in Queensland, Australia.

INTRODUCTION: Release from prison is a period of elevated risk for drug-related harms, particularly among people who inject drugs (PWID). Non-fatal overdose can cause serious morbidity and predicts future fatal overdose, however neither the incidence nor the risk factors for non-fatal overdose following release from prison are well understood. METHODS: Structured health-related interviews were conducted with 1051 adult prisoners in Queensland, Australia prior to release and approximately 1, 3 and 6 months post-release. Incidence of self-reported overdose in the community was calculated for PWID and all prisoners for three discrete time periods. Negative binomial regression with robust error variance was used to identify pre-release predictors of overdose among PWID. RESULTS: The incidence of reported overdose was highest between 1 and 3 months post-release (37.8 per 100 person-years (PY) among PWID; 24.5/100 PY among all ex-prisoners). In adjusted analyses, the risk of post-release non-fatal overdose was higher for PWID who reported: being unemployed for >6 months before prison, having been removed from family as a child, at least weekly use of benzodiazepines and/or pharmaceutical opiates in the 3 months prior to prison, and ever receiving opioid substitution therapy (OST). Pre-release psychological distress and a lifetime history of mental disorder also predicted overdose, whereas risky alcohol use in the year before prison was protective. CONCLUSIONS: PWID have a high risk of overdose following release from prison. Imprisonment is an opportunity to initiate targeted preventive interventions such as OST, overdose prevention training and peer-delivered naloxone for those with a high risk profile.

Rapid beat generation of large-scale zonal flows by drift waves: a nonlinear generic paradigm.

The generalized Charney-Hasegawa-Mima equation is unstable to a four wave modulational instability whereby a coherent, monochromatic drift wave can drive a band of modes and associated zonal flows unstable. Although initially the fastest growing modes dominate, a secondary nonlinear instability later drives the longest wavelength zonal flow and its associated sidebands at twice the growth rate of the fastest growing modulationally unstable modes. This results in a direct transfer from strongly unstable short wavelength modes to the weakly unstable long wavelength modes, which drains the short wavelength pump energy. A related but less efficient direct enstrophy cascade generates very short wavelength modes lying outside the band of modulationally unstable modes.

An investigation into the role of oxygen free radical scavengers in preventing polymethylmethacrylate-induced necrosis in an osteoblast cell culture.

This study examined the effect of polymethylmethacrylate (PMMA) on osteocytic necrosis and the role of free radical scavengers in minimizing this damage. Bovine osteoblast cells with a characteristic phenotype were seeded at a density of 4x10(4) cells/cm2 and cultured in a DMEM supplemented with 10% fetal calf serum. A transwell insert with 2 cc of PMMA was suspended above the culture, and a time log response curve was established following elusion of free radicals around the osteoblast media. Chemiluminescence was used to determine quantitative free radical release. Using a Student's two-tailed t test there was a significant difference in the amount of hydroxyl radical released at 1-6 hours compared with controls (P=.028). Using histologic markers, there was a significant correlation between the use of PMMA and osteoblast cell necrosis. Transwell plates were coated with varying concentrations of mannitol, a known hydroxyl radical scavenger. A log dose response curve was established. There was a clear statistical association between a 10% mannitol solution and a reduction in the free radical release from PMMA (P=.03). Similarly, using Trypan blue histologic staining, there was a significant reduction in PMMA-induced cell necrosis when 10% mannitol was used as a scavenger (P=.01). A Rockwell superficial hardness test was used to determine whether mannitol had any effect on the surface hardness of the polymer. No statistical difference could be found between those treated with mannitol and controls at a depth of up to 1 mm. These results demonstrate hydroxyl radical is released from the polymerization reaction of PMMA. These radicals cause cell death in an osteoblast culture medium. This has been addressed using a 10% mannitol solution, which reduced cell necrosis.